Fantasy writers: do you ever feel paralyzed by the need to research before writing?

For example, let’s say you’re writing a story set in a timeframe that’s different than today though similar to one in the past. But it’s in a fantasy world. You’ll still want to research that similar time period as well as any other important elements which might lend your story some verisimilitude.

Though sometimes, in the midst of researching, it’s easy to forget that you are, indeed, trying to write something that is fictional (and fantasy). How do you get past the need to “know” things, let go and stop worrying about whether your story sounds realistic or not? Especially when it’s just fantasy, at what point does verisimilitude turn your fantasy into historical fiction?

Sometimes I just feel like I can never know enough, and that can become a hinderance to creativity.